Debbie, If the former house had sulfur in the air possibly from cigarette smoke
or maybe even barbaque that would turn silver black. But silver sulfide is not
harmful.
A little history; when Western Electric invented photocells for "talking
pictures" the interior of a glass bulb (60 watt size) was coated with silver
and then had the surface converted to silver sulfide, so that when light
entering the bulb through its narrow window electric current would flow in
proportion to the light value.
In our process the sulfide would speed up the transfer of ions into solution.
That is why I never clean the anode in my brew cells.
"Ole Bob"
